HUNTSVILLE, Alabama -- The magnitude 6.0 earthquake that struck northern California on Sunday morning was measured as far as Alabama, and you might be surprised to know how quickly the shock waves arrived.

According to AlabamaQuake.com, the initial pressure, primary seismic body waves began to arrive about 6 minutes after the quake occurred, and the initial shear, secondary waves were observed after more than 11 minutes. The larger, slower, surface waves began to arrive about 16 minutes following the quake, peaking in amplitude with a maximum vertical ground movement of about 75 micrometers after more than 18 minutes.

The shock waved was measured by instruments at the AlabamaQuake seismic station in Huntsville.

The local seismogram and earthquake epicenter location map have been posted at the AlabamaQuake.com on the "Huntsville Seismograms" and "Recent Earthquake Maps" pages.

The earthquake occurred on Sunday at 5:20 a.m. in the Napa Valley region of northern California, at a location approximately 1,994 miles from Huntsville. The quake had a focal depth of 6.6 miles.

There have been reports of damages and dozens of injuries, some critical, but there have been no reports of fatalities in the epicenter area.

The earthquake occurred near the well-known West Napa Fault, between the Hayward-Rodgers Creek Fault system and the Concord-Green Valley Fault system, part the San Andreas Fault Zone that that lies along the boundary between the Pacific and North American tectonic plates.

The persistent northwestward movement of the Pacific plate relative to the North American plate, at a rate of about 50 millimeters per year, primarily causes a slip movement and a deformation between the major faults.